Android 10 Fastboot not detected AB boot slot

How to change Android system boot slot form A to B fastboot get active slot stack trace: Error: failed to set active slot: Error: {error:{code:1,cmd:fastboot --set-active=b},stderr: waiting for any device > fastboot getvar currentslot Get active system slot fastboot getvar current-slot fastboot getvar all Get active system slot

fastboot set active slot active slot back However, I didn't know which partition slot was currently active A couple